Dear Ted:

Yes. If one is not sorry for their sins then the confession is not valid.

For a confession to be valid the Catholic must...

1) confession all mortal sins and hold nothing back (CCC 1456)

2) the person must be contrite (sorry for sins) and repentant (make a firm purpose of amendment) (CCC 1451)

3) the person must complete the penance assigned to him (CCC 1494)

If a person enters the Sacrament of Confession with conscious and deliberate intention of committing the sin later, then this person is not sorry for his sins and the sin will not be forgiven.

Being sorry for sin means that you wish you had not committed the sin and do not wish to commit it again, EVEN IF you have a good idea that you probably will commit the sin again.

People with addictions have problems with this. An addict may be pretty sure that he will do it again before the day is over. But that is a future assumption.

The clue is if we wish to stop the sin, we want to stop it, and promise to try to not do it again, then our confession is valid. If we do commit the sin again, even a few hours later, then we need to come back to confession.

God Bless,
Bro. Ignatius Mass